《心理語言學(xué)》課件：CH2 brain and language

1、Chapter 2 Brain and LanguageEvolution and Physiology of LanguageHuman language is a complex form of communication.Compared to other species, human language has high productivity.Productivity - the ability to produce new signals to represent new ideas.Language versus CommunicationLanguage is a partic

2、ular form of communicationCommunication can be instinctive or learnedExamples of Animal CommunicationAntsBeesBirdsShort callsSongshttp:/tony/birdsMonkeyshttp:/www.monkeymania.co.uk/gosoundsDolphins and Whales/dolphins/sounds.htmlComparisons Between SpeciesBirds 5-15 different categories of soundPrim

3、ates 20-30 categoriesHumans - unlimitedQuestionsDoes the ability to learn to communicate in a particular way distinguish communication from language?Does mode of communication matter?LanguageHebb (1958) - 3 classes of communication:ReflexivePurposiveLanguage Hocketts Language UniversalsSemanticityLa

4、nguage signals convey meaning through symbolsArbitrariness Arbitrary relationship between the signal and the thing the signal representsDiscretenessLanguage symbols are discrete, distinct, do not vary continuouslyDuality of PatterningLanguage consists of symbols and smaller units that make up the sy

5、mbolsProductivityA few basic elements can be combined in an almost infinite variety of ways to produce novel utterances DisplacementCan communicate about things physically and temporally displacedHow do other species match up on the language universals?SemanticityArbitrarinessDiscretenessDuality of

6、PatterningProductivityDisplacementConclusionPrimates closer to humans in some ways, bees closer in other waysTeaching Language To PrimatesPrimates able to manufacture and use tools; have sophisticated social hierarchies; can learn to solve problems, possibly can think abstractly via conceptsSo if th

7、eyre so smart, why dont they talk?La Mettrie (1747) The ape could become “a perfect little gentleman”Lubbock (1884) Furness (1916)Primate Language ExperimentsKellogg & Kellogg (1933) and Hayes (1951)Vicki only learned to understand a number of spoken words, and could say, after extensive training, m

8、ama, papa, cup, up Chimps vocal tract much different!LarynxAdams appleLarynxHuman mouth is highly evolved to enable speechLarynx is deep in a long neck - risking choking (kills thousands each year)Jaw is short and less efficient for chewing than in other primates - hence painful wisdom teethChimpHum

9、anEvolution of Speech AbilityNeed to control breathingLarynx is deep but doesnt fossilizeBut base of skull is flexed only in modern humansH. erectus did not have thoracic enlargement of spinal chord thought to be associated with speech and breathing controlVocal ChordsOpen - for breathingClosed duri

10、ng speechNonverbal CommunicationGardner & Gardner (1969; 1975; 1984) WashoeWashoe tributeKokoAll communication was in ASL(手勢語）Would sign spontaneously sometimesWould sign by herselfClaimed she learned 132 ASL signsWould string signs together - e.g., more cookie, you tickle me Washoe, open food drink

11、 (when by a fridge)Some evidence that chimps use ASL among themselvesDid Washoe have true language?Dont know. Some evidence for novel generativityHowever, is her communication cognitively driven? Premack (1971) and Sarah“Taught to communicate with plastic symbols on a magnetic boardTaught to write s

12、entences, appeared to exhibit generativity, comprehensionProblem: no evidence that she was doing anything more than getting rewardsProblem: no evidence she understood that some orders not permissibleSavage-Rumbaugh (1993) and “Kanzi”Claimed a large vocabulary and ability to use word order to express

13、 meaning - lexigramsKanziTerrace (1979) Nim ChimpskyTaught ASL. Videotaped thousands of interactions with trainers.Restricted to short utterances of 1-2 signslong utterances seem redundant, e.g., give orange me give eat orange me eat orange give me eat orange give me you“Many signs were imitations o

14、f signs first given by his trainerDid not take turns in conversation“Conclusion: little evidence for communication in phrases or sentencesThe Washoe TapesThen, Terrace analyzed some of the Washoe tapes. said the same thing was going on.Utterance length never changed much over timeMuch repetition Pro

15、blems in this ResearchMuch time and effort involved; learn more slowly than humanssigns overestimatedLimited variety of utterancesAnecdotes and gross statisticsExperimenter bias leads to over-interpretationDolphins and Syntax(Akeakamai and Phoenix)Herman et al. (1993) trained to respond to a symboli

16、c language of objects and actions. They respond to novel sentences.However, they cannotRefer to abstract conceptsCombine small meaningful elements into larger meaningful elementsOrganize communicative elements into a systematic grammar Refer to things in the past and the futureStore meanings of hund

17、reds of thousands of concepts and map them onto specific combinations of vocal patternsThe Human BrainShort history of researchDateEvent1836Abercrombie?1836Marc Dax claimed that the LH of right-handers has “memory for words”1861Paul Broca claimed that the LH of right-handers has “faculty of articula

18、te speech”1874Karl Wernicke discovered that damage to a certain area could cause receptive aphasia.John Hughlings Jackson claimed that the LH is responsible for language, while the RH is responsible for visual cognition (recognition, discrimination, recall).WWI-IIMany observations of the cognitive r

19、esults of head injuriesend WWIIJuhn A. Wada developed carotid amytal test for cerebral dominance for speech1950sPenfield & Wilder use cortical stimulation to map the cortex treat epilepsy, discover the motor-sensory homunculus1960sCorpus callosotomy (commissurotomy) split-brain patients1970sHemifiel

20、d tachistoscopy, dichotic listening laterality research1980s Noninvasive imaging techniquesPhrenologyThe localisation hypothesis dates back to the pre-scientific theories of Phrenology (Franz Joseph Gall.Bumps on the outer surface of the skull are not a reliable guide to the relative size or shape o

21、f the underlying brain regions.The Brain in 18361836: George Combe (1788-1858)1 of 13 children to an Edinburgh Brewer.Reported that if an injury exposed the brain, physically touching the exposed area could cause rather precise alterations in mental functionAnticipates intracranial stimulation and E

22、EG in the 1940sAlso, reported a visible swelling (increase in blood flow) during mental activityAnticipates the basis of FMRI by 150 years!Brain BasicsGroups of neurons, interconnected by synapses, form neural networks. The organization of the human brain for languageStanford Report, February 25, 20

23、03The Brain Function forLanguage and ReadingNeurolinguistics Neurolinguistics is the study of the neural mechanisms in the human brain that control the comprehension, production, and acquisition of language. As an interdisciplinary field, neurolinguistics draws methodology and theory from fields suc

24、h as neuroscience, linguistics, cognitive science, neurobiology, communication disorders, neuropsychology, and computer science. Neurolinguists study the physiological mechanisms by which the brain processes information related to language, and evaluate linguistic and psycholinguistic theories, usin

25、g aphasiology, brain imaging, electrophysiology, and computer modeling.Neurolinguistics is historically rooted in the development in the 19th century of aphasiology, the study of linguistic deficits (aphasias) occurring as the result of brain damage. Aphasiology attempts to correlate structure to fu

26、nction by analyzing the effect of brain injuries on language processing. One of the first people to draw a connection between a particular brain area and language processing was Paul Broca, a French surgeon who conducted autopsies on numerous individuals who had speaking deficiencies, and found that

27、 most of them had brain damage (or lesions) on the left frontal lobe, in an area now known as Brocas area. Later, Carl Wernicke, proposed that different areas of the brain were specialized for different linguistic tasks, with Brocas area handling the motor production of speech, and Wernickes area ha

28、ndling auditory speech comprehension. The work of Broca and Wernicke established the field of aphasiology and the idea that language can be studied through examining physical characteristics of the brain. Neurolinguistics research investigates several topics, including where language information is

29、processed, how language processing unfolds over time, how brain structures are related to language acquisition and learning, and how neurophysiology can contribute to speech and language pathology. Researchers are drawn to the field from a variety of backgrounds, bringing along a variety of experime

30、ntal techniques as well as widely varying theoretical perspectives. Much work in neurolinguistics is informed by models in psycholinguistics and theoretical linguistics, and is focused on investigating how the brain can implement the processes that theoretical and psycholinguistics propose are neces

31、sary in producing and comprehending language Overview of methodologiesLesionsWada testCraniotomy & cortical stimulationCorpus callosotomy & split-brain patientsHemifield tachistoscopyDichotic listeningImaging: C(A)T, PET, (f)MRIElectromagnetic: EEG, MEG - not todayTranscranial magnetic stimulation (

32、TMS)LesionsA lesion is a non-specific term referring to abnormal tissue in the body. It can be caused by any disease process including trauma (physical, chemical, electrical), infection, neoplasm, metabolic and autoimmune.Wada testThe Wada test (named for a neurologist, Juhn A. Wada) consists of beh

33、avioral testing after the injection of an anesthetic into the right or left internal carotid artery. Depending on how the injection is made (and the quantity), there is a certain amount of time during which the activities of one of the cerebral hemispheres are suspended, so the abilities subserved b

34、y the other hemisphere can be tested in isolation. Craniotomy & cortical stimulationA craniotomy is a surgical operation in which part of the skull, called a skull flap, is removed in order to access the brain. Craniotomies are necessary for many types of surgery; they are also widely used in neuros

35、cience in techniques such as extracellular recording, brain imaging, and manipulations such as electrical stimulation and chemical titration.Human craniotomy is usually performed under general anesthesia but can be also done with the patient awake using a local anaesthetic and generally does not inv

36、olve significant discomfort for the patient. Corpus callosotomy (split-brain patients)“Split-brain” is a lay term to describe the result of severing the corpus callosum to some degree. The surgical operation to produce this condition is called corpus callosotomy. It is rarely performed, usually only

37、 in the case of epilepsy, in order to mitigate the risk of accidental physical injury by reducing the severity and violence of epileptic seizures.Corpus callosotomy (split-brain patients), cont.A patient with a split brain, when shown an image in his or her left visual field (the left half of what e

38、ach eye sees), will be unable to name what he or she has seen. This is because the speech control center is in the left side of the brain in most people and the image from the left visual field is sent only to the right side of the brain. Since the two sides of the brain cannot communicate, the pati

39、ent cant name what he or she is seeing. The person can, however, pick up a corresponding object with their left hand, since that hand is controlled by the right side of their brain.Divided visual-field (hemifield) tachistoscopyA tachistoscope is a device that displays (usually by projecting) an imag

40、e for a specific amount of time. It can be used to increase recognition speed, to show something too fast to be consciously recognized, or to test which elements of an image are memorable. Actual tachistoscopes use a slide or transparency projector equipped with the mechanical shutter system typical

41、 of a camera. The slide is loaded, the shutter locked open, and focusing and alignment are adjusted, then the shutter is closed. When ready for the test, a shutter speed is selected, and the shutter is tripped normally.Divided visual-field (hemifield) tachistoscopy, cont.Before computers became ubiq

42、uitous, tachistoscopes were used extensively in psychological research to present visual stimuli for controlled durations. Some experiments employed pairs of tachistoscopes so that an experimental participant could be given different stimulation in each visual field.Dichotic listeningDichotic Listen

43、ing is a procedure commonly used for investigating selective attention in the auditory domain. Two messages are presented to both the left and right ears (one message to each ear), normally using a set of headphones. Normally, participants are asked to pay attention to either one, or both (divided a

44、ttention condition) of the messages and may later be asked about the content of both.It was developed to mimic processing demands in the natural world, where sensory overload is common. Consider the cocktail party or, more appropriate for today, the wine-tasting party. We may attempt to speak with o

45、ne individual, but the speakers voice is intermixed with a multitude of incoming auditory signals: conversations going on about us, music from the compact disc player, the clatter of plates being filled at the buffet table, the children watching a video in the next room. Despite this cacophony of so

46、und, we are quite proficient at focusing on the relevant signalthe words being spoken by our conversational partner.Dichotic listening, cont.In the seminal study of Kimura (1961a), the stimuli were digits, presented so that one digit was heard in the left ear at the same time as a second digit was h

47、eard in the right ear. Kimura found that people were much more likely to report having heard the stimuli presented to the right ear, an effect dubbed the right-ear advantage. Kimuras usage of dichotic listening to confirm the lateralization of language to the left hemisphere in normal subjects was s

48、oon substantiated by studies with lesioned subjects. Kimura (1961b) showed that patients with left temporal lobe lesions performed worse at the task than did patients with right temporal lobe lesions. In addition, split-brain patients showed a considerable right ear advantage in a study using words

49、as stimuli. They succeeded in recognizing words presented to the right ear, but performed no better than chance for words presented to the left ear, see Milner, Taylor, and Sperry (1968) and Sparks and Geschwind (1968).Electro-encephalogram，EEGElectrophysiological techniques take advantage of the fa

50、ct that when a group of neurons in the brain fire together, they create an electric dipole or current. The technique of EEG measures this electrical current using sensors on the scalp, 腦電圖原理將人體腦組織生物電活動放大記錄的一門技術(shù)，通過腦電圖描記儀將腦自身微弱的生物電放大后記錄在專門的紙上，即得出有一定波形、波幅、頻率和位相的圖形、曲線，即為腦電圖。當(dāng)腦組織發(fā)生病理或功能改變時，這種曲線即發(fā)生相應(yīng)的改變，從

51、而為臨床診斷、治病提供依據(jù)。Computerized (Axial) Tomography (CT/CAT)計算機斷層掃描原理不同頻率的電磁波性能不同。X射線穿透性強，且與物質(zhì)的密度有關(guān)，即不同物質(zhì)對X射線的吸收系數(shù)不同。使X射線穿過腦的橫斷層面，由于不同組織對X射線的吸收系數(shù)不同，衰減后的X射線照射到感光物質(zhì)上，形成差異。通過變換掃描的角度與橫斷層面，計算機接收這種二維多層差異，經(jīng)過計算重建成腦的三維切面影像?？勺⑸鋵Ρ榷仍鰪妱┗蛉玖稀＿m用于急性頭面外傷、腦溢血或腦血管梗塞、占位性病變、急性（72小時內(nèi)，保持原發(fā)性）神經(jīng)性功能障礙等診斷。Computed tomography (CT), o

52、riginally known as computed axial tomography (CAT or CT scan), employs tomography (digital geometry processing) to generate a 3D image of the internals of an object from a large series of two-dimensional X-ray images taken around a single axis of rotation. Positron Emission Tomography (PET)To produc

53、e a PET scan, a patient is administered a solution of a metabolically-active substance, such as glucose, tagged with a positron-emitting isotope. The substance eventually makes its way to the brain and concentrates in areas of high metabolism and blood flow, which are presumably triggered by increas

54、ed neural activity. The positrons emitted by the isotopes are collected by detectors arrayed around the patients body and converted into signals which are amplified and sent to a computer for construction of an image.PET的依據(jù)是一些放射性同位素標(biāo)記的分子（如含18F的脫氧葡萄糖FDG）能正常地參加腦細胞的新陳代謝。這些同位素發(fā)射正電子，正電子不穩(wěn)定，易與負電子撞擊而湮滅，所生能

55、量以雙向-射線方式釋放。測量這兩束-射線的量，即可知該標(biāo)記同位素分子的含量，從而作為該部位功能活動是否增強的標(biāo)記。優(yōu)點：可觀察動態(tài)過程。Positron Emission Tomography (PET)Right hemisphere seizurePET vs CTPET differs from CT in that it uses the bodys basic biochemistry to produce images. The positron-emitting isotope is chosen from elements that the body already uses,

56、 such as carbon, nitrogen, oxygen, and fluorine. By relying on normal metabolism, PET is able to show a biochemical change even in diseases such as Alzheimers in which there is no gross structural abnormality. Magnetic Resonance Imaging (MRI)磁共振成像原理強磁場會導(dǎo)致機體組織的原子依磁性而順序排列。當(dāng)射頻電磁波照射頭部時，會激發(fā)頭組織的原子發(fā)射它們自己的射

57、頻電磁波，這就是磁共振信號。它可被三維梯度磁場檢測出來并發(fā)送給計算機，計算機處理并編輯這種信息重建為腦的三維圖像。分辨率高于CT。Magnetic Resonance Imaging (MRI)In 1977, a team lead by Raymond Damadian produced the first image of the interior of the human body with a prototype device using nuclear magnetic resonance. Damadians device uses liquid helium to superc

58、ool magnets in the walls of a cylindrical chamber. A subject is introduced into the chamber and so exposed to a powerful magnetic field. This magnetic field has a particular effect on the nuclei of hydrogen atoms in the water which all cells contain that forms the basis of the imaging technique.Magn

59、etic Resonance Imaging (MRI)All atoms spin on their axes. Nuclei have a positive electronic charge, and any spinning charged particle will act as a magnet with north and south poles located on the axis of spin. The spin-axes of the nuclei in the subject line up with the chambers field, with the nort

60、h poles of the nuclei pointing in the southward direction of the field. Then a radio pulse is broadcast toward the subject. The pulse causes the axes of the nuclei to tilt with respect to the chambers magnetic field, and as it wears off, the axes gradually return to their resting position (within th